1. Field of the Invention
The present invention relates to a magnetic recording/reproduction apparatus used as a hard disk apparatus and, more particularly, to a magnetic recording/reproduction apparatus using perpendicular magnetization and a perpendicular magnetic recording medium for use in the apparatus.
2. Description of the Related Art
An amorphous rare earth element-transition metal alloy magnetic layer having perpendicular magnetic anisotropy is generally used as a recording layer of a magnetooptical recording medium.
Recently, the use of this amorphous rare earth element-transition metal alloy magnetic film as a perpendicular magnetic recording layer of a perpendicular magnetic recording medium such as a hard disk is proposed in, e.g., Jpn. Pat. Appln. KOKAI Publication Nos. 5-54358 and 2001-76332. However, the amorphous rare earth element-transition metal alloy magnetic layer is a continuous layer having no segregated structure, i.e., having neither magnetic crystal grains nor grain boundaries. Therefore, if this layer is used as a magnetic recording medium, there is no core for keeping a written signal in a written place. As a consequence, a recorded signal shifts or disappears. This phenomenon often occurs especially in high-frequency recording, so the amorphous rare earth element-transition metal alloy magnetic layer is unsuited to increasing the recording density of perpendicular magnetic recording.
Jpn. Pat. Appln. KOKAI Publication No. 2002-25031 discloses a perpendicular magnetic recording medium having a multilayered arrangement obtained by combining a material such as CoCr used in the conventional magnetic recording medium and the amorphous rare earth element-transition metal alloy magnetic layer. Unfortunately, even this medium has the problem that the medium noise is larger than in the conventional recording medium using a CoCr recording layer.
As described above, a perpendicular magnetic recording layer using the conventional rare earth element-transition metal alloy magnetic layer is unsuitable to increasing the recording density and is unpractical because the medium noise is large.